handle text output in OpenMaple - Maple Help

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textCallBack - handle text output in OpenMaple

Calling Sequence

textCallBack(data, tag, output)




user_data pointer passed to StartMaple (void*)



code indicating kind of text (int)



output string (char*)



This OpenMaple function is part of the MCallBackVector structure passed as an argument to StartMaple.


The textCallBack function is called with typical (non-exceptional) Maple output. The output that Maple generates, for example, an intermediate result or the output from a printf statement, is passed to the textCallBack function.


The prototype for the function you can assign to the entry in the MCallBackVector must look like the following.

void M_DECL textCallBack( void *data, int tag, char *output );


The tag parameter indicates the type of Maple output. The tag parameter can take one of the following values (as defined in maplec.h).


A line-printed (1-D) Maple expression or statement.




Diagnostic output (high printlevel or trace output).




Miscellaneous output, for example, from the Maple


printf function.




Text help output. This is generated in response to a


help request.  For a more comprehensive help


facility, see MapleHelp.




Response to a Maple quit, done, or stop command.




A warning message generated during a computation.




An error message generated during parsing or


processing. This is generated only if you


do not specify an errorCallBack function.




Kernel resource usage status (a "bytes used"


message). This is generated only if you


do not specify a statusCallBack function.




Output from the Maple debugger.




The output parameter contains the output of the type indicated by the tag parameter. Each output string can be arbitrarily long.  Most output obeys interface(screenwidth), which is initially set to infinity.  Some output is not line-broken, including output generated by printf (which control its own formatting).


A single result may be split into multiple calls to the textCallBack function. In particular, this can happen when interfacescreenwidth is not infinity.  It is also true for formatted output like that generated by accessing help.  A single command can generate many calls with different output tags.


The data parameter contains the same data as passed to StartMaple in the user_data parameter.


Source code for a textCallBack example is provided in the samples/OpenMaple/HelpExamples subdirectory of your Maple installation.

See Also

callBackCallBack, CustomWrapper, errorCallBack, interface, OpenMaple, OpenMaple/C/API, OpenMaple/C/Examples, queryInterrupt, readLineCallBack, redirectCallBack, StartMaple, statusCallBack, streamCallBack

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